Since our original work on the propagation of human trabecular cells for glaucoma research, we have been carefully monitoring potential alterations in the cells due to the in vitro environment. Limitations on the ability to repeatedly passage these cells without loss of mitotic potential and changes in morphology have prompted us to perform detailed evaluations of the ultrastructural features of individual trabecular cell lines to assure that the differentiated features of this cell type have been preserved. Cells from the younger patients and specialized growth factors appear particularly useful for biochemical and physiological studies of the normal properties of trabecular cells. Improved cell culture methodology may be essential to obtain suitable cultures of trabecular cells from patients with POAG and other sources which show a reduced mitotic potential. We plan to continue in our efforts to (1) define improved conditions for cell growth; (2) examine important physiological responses of the trabecular cells, such as phagocytosis and connective tissue production; and (3) evaluate the mechanisms by which glucocorticoids, prostaglandins, and cytochalasins may exert pharmacological effects on the outflow pathway. Quantitative assessment of cell division and electron microscopic observations will be employed in our studies of oxidative damage and other ;mechanisms of cell injury which may be related to the development of reduced outflow facility in POAG and aging. In addition, studies designed to evaluate the biochemical specificity of trabecular cells, including studies of cellular and cell surface proteins, cytoarchitecture, and the production and testing of monoclonal antibodies may add important new information. By comparing data obtained from cultured cells to that obtained from excised human trabecular tissue, we hope to better understand the prospects and limitations of the trabecular meshwork call culture system.